Hi bitbitt,
welcome to the Apple (user-0to-user) Community!
Re: "I want to buy some in-game money for my game"
"I can do everything but purchase in-game money how to fix, please?"
There may be a Screen Time setting that restricts purchases
You may want to check whether any restrictions are set:
Manage App Store purchases, settings, and restrictions on iPhone - Apple Support
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Re: "I’ve tried again and again, everything".
Your Apple Account is the account you use to access Apple services like the App Store, Apple Music, iTunes, iCloud, iMessage, FaceTime, and more. It includes the email address and password you use to sign in as well as the contact, payment, and security details you use across Apple services.
You can check you are signed in to your iPhone with the Apple ID you will use for purchases:
See how to: Sign in to your Apple Account - Apple Support
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Re: “The iTunes Store is unable to process purchases at this time. Please try again later.”
Apple requires that a payment method is listed in your Apple Account for the first time you use the App Store or iTunes.
You can check which Payment methods Apple can accept in your country or region from the link blolw:
Payment methods that you can use with your Apple Account - Apple Support
and
If you want to add an Apple Account payment method:
See how to: Add a payment method to your Apple Account - Apple Support
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If needed: Info. on how in-app purchases work:
See how to: Buy additional app features with in-app purchases and subscriptions - Apple Support
or
What to do: If you can't find or use your in-app purchases - Apple Support
All the best :-)
